BOARD_INDICATE_ARMED_STATE was only set during arming, so an external
component might have reset the board during param save, leading to param
loss.
This extends the API to trigger the arming state also while the shutdown
lock is taken.
- simple state machine to reset, configure, etc
- checked register mechanism (sensor will reset itself on configuration error)
- configured in 16 bit mode (1320 LSB/Gauss instead of 330 LSB/Gauss)
- adjusted orientation handling in driver to match datasheet as closely as possible
- in many external compass units the rotation was wrong and very difficult to actual determine how to set correctly